Horizontal shaft impact crushers are commonly employed to pulverize many different types of materials including, by way of example rather than limitation, asphalt, concrete, and rock. Such crushers typically include a frame, a crushing cavity, and a rotor disposed within the cavity and supporting a number of impeller bars. Typically, the rotor includes a plurality of discs that are axially spaced relative to the rotational axis of the rotor, with each of the discs having a number of recesses in which the impeller bars are mounted. The rotor is typically driven by an external drive mechanism.
The rotor and the attached impeller bars are generally surrounded by a number of breaker plates. The frame includes a feed opening to permit the material to be fed into the crushing cavity, such that the material comes into contact with the impeller bars of the rotating rotor. The impeller bars repeatedly throw the material against the breaker plate(s), thereby breaking the material into smaller pieces.
As is known, the impeller bars must be adjusted periodically to account for wear. Eventually, the impeller bars must be replaced altogether. Thus, there must a mechanism to provide for the easy adjustment and/or the eventual removal of the impeller bars from the rotor.
Many impeller bars are secured to the rotor using a wedge assembly that secures the impeller bars within the recess. The wedge is typically oriented such that the tendency of the impeller bar to slide radially away from the axis of the rotor is resisted by the wedge bearing against a portion of the recess. The wedge and the recess are shaped such that the gripping forces of the wedge(s) against the impeller bar actually increase as the impeller bar slides moves (e.g., slides radially outwardly). Thus, the impeller bar(s) actually gets tighter after the crusher has been started.
However, the impeller bars and the wedges might not be fully secured until after start up of the crusher. Thus, it is desirable to ensure that the wedges and impeller bars are at least temporarily secured prior to start up of the crusher.